Synthesis and characterization of polyaniline salts with phenoxy acetic acids by emulsion polymerization

Polyaniline salts have been synthesized by chemical oxidative polymerization of aniline in the presence of phenoxy acetic acid and its two derivatives using emulsion method at room temperature and characterized by different techniques such as infrared, H-1 and C-13 NMR, UV-visible spectroscopy, SEM, wide angle X-ray diffractograms and conductivity measurements. These polyaniline salts have the desirable property of high solubility for processibility in solvents such as DNIF, DMSO and a mixture of CHCl3 and acetone and they exhibit fairly good conductivity of similar to 3.0 x 10(-3) S cm(-1). The variations in solubility, conductivity and morphology with the protonating strength of the dopants are examined.

Synthesis, sintering and microstructural characterization of nanocrystalline Hydroxyapatite Composites

Nanocrystalline hydroxyapatite (HAp) exhibits better bioactivity and biocompatibility with enhanced mechanical properties compared to the microcrystalline counterpart. In the present work, nanocrystalline hydroxyapatite was synthesized by wet chemical method. Sintering was carried out with nanocrystalline alumina as additive, the content of alumina being varied from 10 to 30 wt% in the composite. For 20 and 30 wt % Al2O3, hydroxyapatite decomposed into tricalcium phosphate (TCP) above the sintering temperature of 1100 degrees C. The fracture toughness of nano HAp-nano Al2O3 composite is anisotropic in nature and reached a maximum value of 6.9 MPa m(1/2).

Characterization of the human SLC22A18 gene promoter and its regulation by the transcription factor Sp1

SLC22A18, a poly-specific organic cation transporter, is paternally imprinted in humans and mice. It shows loss-of-heterozygosity in childhood and adult tumors, and gain-of-imprinting in hepatocarcinomas and breast cancers. Despite the importance of this gene, its transcriptional regulation has not been studied, and the promoter has not yet been characterized. We therefore set out to identify the potential cis-regulatory elements including the promoter of this gene. The luciferase reporter assay in human cells indicated that a region from -120 by to +78 by is required for the core promoter activity. No consensus TATA or CHAT boxes were found in this region, but two Sp1 binding sites were conserved in human, chimpanzee, mouse and rat. Mutational analysis of the two Sp1 sites suggested their requirement for the promoter activity. Chromatin-immunoprecipitation showed binding of Sp1 to the promoter region in vivo. Overexpression of Sp1 in Drosophila Sp1-null SL2 cells suggested that Sp1 is the transactivator of the promoter. The human core promoter was functional in mouse 3T3 and monkey COS7 cells. We found a CpG island which spanned the core promoter and exon 1. COBRA technique did not reveal promoter methylation in 10 normal oral tissues, 14 oral tumors, and two human cell lines HuH7 and A549. This study provides the first insight into the mechanism that controls expression of this imprinted tumor suppressor gene. A COBRA-based assay has been developed to look for promoter methylation in different cancers. The present data will help to understand the regulation of this gene and its role in tumorigenesis. (C) 2008 Elsevier B.V. All rights reserved.

Characterization of the human SLC22A18 gene promoter and its regulation by the transcription factor Sp1

SLC22A18, a poly-specific organic cation transporter, is paternally imprinted in humans and mice. It shows loss-of-heterozygosity in childhood and adult tumors, and gain-of-imprinting in hepatocarcinomas and breast cancers. Despite the importance of this gene, its transcriptional regulation has not been studied, and the promoter has not yet been characterized. We therefore set out to identify the potential cis-regulatory elements including the promoter of this gene. The luciferase reporter assay in human cells indicated that a region from -120 by to +78 by is required for the core promoter activity. No consensus TATA or CHAT boxes were found in this region, but two Sp1 binding sites were conserved in human, chimpanzee, mouse and rat. Mutational analysis of the two Sp1 sites suggested their requirement for the promoter activity. Chromatin-immunoprecipitation showed binding of Sp1 to the promoter region in vivo. Overexpression of Sp1 in Drosophila Sp1-null SL2 cells suggested that Sp1 is the transactivator of the promoter. The human core promoter was functional in mouse 3T3 and monkey COS7 cells. We found a CpG island which spanned the core promoter and exon 1. COBRA technique did not reveal promoter methylation in 10 normal oral tissues, 14 oral tumors, and two human cell lines HuH7 and A549. This study provides the first insight into the mechanism that controls expression of this imprinted tumor suppressor gene. A COBRA-based assay has been developed to look for promoter methylation in different cancers. The present data will help to understand the regulation of this gene and its role in tumorigenesis. (C) 2008 Elsevier B.V. All rights reserved.

Characterization of a continuous CO2 laser-welded Fe-Cu dissimilar couple

Continuous CO2 laser welding of an Fe-Cu dissimilar couple in a butt-weld geometry at different process conditions is studied. The process conditions are varied to identify and characterize the microstructural features that are independent of the welding mode. The study presents a characterization of the microstructure and mechanical properties of the welds. Detailed microstructural analysis of the weld/base-metal interface shows features that are different on the two sides of the weld. The iron side can grow into the weld with a local change in length scale, whereas the interface on the copper side indicates a barrier to growth. The interface is jagged, and a banded microstructure consisting of iron-rich layers could be observed next to the weld/Cu interface. The observations suggest that solidification initiates inside the melt, where iron and copper are mixed due to convective flow. The transmission electron microscopy (TEM) of the weld region also indicates the occasional presence of droplets of iron and copper. The microstructural observations are rationalized using arguments drawn from a thermodynamic analysis of the Fe-Cu system.

Preparation, characterization and thermal decomposition of praseodymium, terbium and neodymium carbonates

The preparation of three different types of carbonates of praseodymium, neodymium and terbium has been described. The carbonates have been characterized by potentiometry, chemical analysis, X-ray crystallography, infra-red spectroscopy and by their thermal behaviour. The thermal decomposition of several carbonates has been studied exhaustively under a variety of conditions and the stoicheiometry, thermodynamics and energetics of the reactions at various stages of decomposition have been examined. The stoicheiometry of the oxides obtained as final products of decomposition has been examined.

Biochemical Characterization Of Β-N-Oxalyl-L-Α,Β-Diaminopropionic Acid, The Lathyrus Sativus Neurotoxin As An Excitant Amino Acid

Abstract—β-N-Oxalyl-l-α,β-diaminopropionic acid (ODAP), the toxin isolated from the seeds of Luthyrus sativus produces head retraction, tremors and convulsions when injected into a variety of experimental animals. In 12-day-old rats, it has been found that the convulsive behaviour is accompanied by profound biochemical changes in the brain. The brain homogenates prepared from ODAP injected animals show a higher rate of respiration. There is a decrease in the brain glucose, glycogen, ATP, phosphocreatine and acetylcholine levels of the convulsing animals. The inorganic phosphate, lactic acid and acetylcholineesterase levels increase. These results establish that ODAP is a typical convulsant.

The Isolation and Characterization of β-N-Oxalyl-L-α,β-Diaminopropionic Acid: A Neurotoxin from the Seeds of Lathyrus sativus

A neurotoxic compound has been isolated from the seeds of Lathyrus sativus in 0.5% yield and characterized as β-N-oxalyl-L-α,β-diaminopropionic acid. The compound is highly acidic in character and forms oxalic acid and diaminopropionic acid on acid hydrolysis. The compound has a specific rotation of -36.9° and has apparent pK values in the order of 1.95, 2.95, and 9.25, corresponding to the two carboxyl and one amino functions, respectively. The compound has been synthesized by reacting an aqueous methanolic solution of the copper complex of L-α,β-diaminopropionic acid prepared at pH 4.5-5.0 with dimethyl oxalate under controlled pH conditions and isolating the compound by chromatography on a Dowex 50-H+ column after precipitating the copper. The compound induced severe neurological symptoms in day-old chicks at the level of 20 mg/chick, but not in rats or mice. It also inhibited the growth of several microorganisms and of the insect larva Corcyra cephalonica Staint. L-Homoarginine had no neural action in chicks. It is suggested that the neurotoxic compound is species specific in its action and may be related to "neurolathyrism" associated with the human consumption of L. sativus seeds.

Site characterization model using least-square support vector machine and relevance vector machine based on corrected SPT data (N-c)

Statistical learning algorithms provide a viable framework for geotechnical engineering modeling. This paper describes two statistical learning algorithms applied for site characterization modeling based on standard penetration test (SPT) data. More than 2700 field SPT values (N) have been collected from 766 boreholes spread over an area of 220 sqkm area in Bangalore. To get N corrected value (N,), N values have been corrected (Ne) for different parameters such as overburden stress, size of borehole, type of sampler, length of connecting rod, etc. In three-dimensional site characterization model, the function N-c=N-c (X, Y, Z), where X, Y and Z are the coordinates of a point corresponding to N, value, is to be approximated in which N, value at any half-space point in Bangalore can be determined. The first algorithm uses least-square support vector machine (LSSVM), which is related to aridge regression type of support vector machine. The second algorithm uses relevance vector machine (RVM), which combines the strengths of kernel-based methods and Bayesian theory to establish the relationships between a set of input vectors and a desired output. The paper also presents the comparative study between the developed LSSVM and RVM model for site characterization. Copyright (C) 2009 John Wiley & Sons,Ltd.

Characterization of two M17 family members in Escherichia coli, Peptidase A and Peptidase B

Escherichia coil encodes two aminopeptidases belonging to the M17 family: Peptidase A (PepA) and Peptidase B (PepB). To gain insights into their substrate specificities, PepA or PepB were overexpressed in Delta pepN, which shows greatly reduced activity against the majority of amino acid substrates. Overexpression of PepA or PepB increases catalytic activity of several aminopeptidase substrates and partially rescues growth of Delta pepN during nutritional downshift and hightemperature stress. Purified PepA and PepB display broad substratespecificity and Leu, Lys, Met and Gly are preferred substrates. However, distinct differences are observed between these two paralogs: PepA is more stable at high temperature whereas PepB displays broader substrate specificity as it cleaves Asp and insulin B chain peptide. Importantly, this strategy, i.e. overexpression of peptidases in Delta pepN and screening a panel of substrates for cleavage, can be used to rapidly identify peptidases with novel substrate specificities encoded in genomes of different organisms. (C) 2010 Elsevier Inc. All rights reserved.

Nitrosation of N,N′-ethylenebis-(acetylacetoneimine) complexes of copper (II) and nickel(II) and characterization of the products

Isonitroso derivatives of copper(II) and nickel(II) complexes of N,N′-ethylenebis(acetylacetoneimine) have been prepared by nitrosation of the respective complexes using nitric oxide as well as nitrite ion. The condensation of isonitrosoacetylacetone in the presence and in the absence of nickel(II) has been investigated. The i.r. and electronic spectra and magnetic moment of the nickel(II) and copper(II) complexes have been studied. The nature of bonding of the ligand to the metal ion is discussed. The complexes have planar structures.

Isolation and partial characterization of sheep plasma α1-mucoprotein

1. 1. Sheep plasma α1-mucoprotein was isolated in an electrophoretically homogeneous state by a combination of ammonium sulphate saturation, isoelectric precipitation and preparative agar electrophoresis in a yield of approx. 150 mg/l of plasma. 2. 2. The mucoprotein was water-soluble, non-coagulable on heating at 100°, not precipitable by 1.8 M perchloric acid, 10% trichloroacetic acid but precipitable by saturated ammonium sulphate solution, 0.6 M sulfosalicylic acid and 5% phosphotungstic acid in 2 N HCl. It had E1 cm1 % value of 9.57 at 278 mμ in water, refractive-index index increment 1.9·10-4 (g/l) in water, isoelectric point at pH 4.45 (sodium acetate-acetic acid buffer) and was homogeneous in pH range 4.0-11.5 but at pH values 2.6 and 3.5 showed some dissociation. 3. 3. The mucoprotein had the following chemical composition: Nitrogen, 12.4%; polypeptide, 77.4%; total hexose (only mannose and galactose), 7.1%; fucose, 1.0%; glucosamine, 4.9% and sialic acid, 4.8%. It had no N-terminal amino acid.

Loading of itraconazole into porous silica and silicon microparticles: characterization and dissolution tests

Most new drug molecules discovered today suffer from poor bioavailability. Poor oral bioavailability results mainly from poor dissolution properties of hydrophobic drug molecules, because the drug dissolution is often the rate-limiting event of the drug’s absorption through the intestinal wall into the systemic circulation. During the last few years, the use of mesoporous silica and silicon particles as oral drug delivery vehicles has been widely studied, and there have been promising results of their suitability to enhance the physicochemical properties of poorly soluble drug molecules. Mesoporous silica and silicon particles can be used to enhance the solubility and dissolution rate of a drug by incorporating the drug inside the pores, which are only a few times larger than the drug molecules, and thus, breaking the crystalline structure into a disordered, amorphous form with better dissolution properties. Also, the high surface area of the mesoporous particles improves the dissolution rate of the incorporated drug. In addition, the mesoporous materials can also enhance the permeability of large, hydrophilic drug substances across biological barriers. T he loading process of drugs into silica and silicon mesopores is mainly based on the adsorption of drug molecules from a loading solution into the silica or silicon pore walls. There are several factors that affect the loading process: the surface area, the pore size, the total pore volume, the pore geometry and surface chemistry of the mesoporous material, as well as the chemical nature of the drugs and the solvents. Furthermore, both the pore and the surface structure of the particles also affect the drug release kinetics. In this study, the loading of itraconazole into mesoporous silica (Syloid AL-1 and Syloid 244) and silicon (TOPSi and TCPSi) microparticles was studied, as well as the release of itraconazole from the microparticles and its stability after loading. Itraconazole was selected for this study because of its highly hydrophobic and poorly soluble nature. Different mesoporous materials with different surface structures, pore volumes and surface areas were selected in order to evaluate the structural effect of the particles on the loading degree and dissolution behaviour of the drug using different loading parameters. The loaded particles were characterized with various analytical methods, and the drug release from the particles was assessed by in vitro dissolution tests. The results showed that the loaded drug was apparently in amorphous form after loading, and that the loading process did not alter the chemical structure of the silica or silicon surface. Both the mesoporous silica and silicon microparticles enhanced the solubility and dissolution rate of itraconazole. Moreover, the physicochemical properties of the particles and the loading procedure were shown to have an effect on the drug loading efficiency and drug release kinetics. Finally, the mesoporous silicon particles loaded with itraconazole were found to be unstable under stressed conditions (at 38 qC and 70 % relative humidity).

Sol-Gel Synthesis, characterization and optical properties of Tio2 thin films deposited on ITO/Glass substrates

TiO2 thin films have been deposited on glass and indium tin oxide (ITO) coated glass substrates by sol-gel technique. the influence of annealing temperature on the structural , morphological and optical properties has been examined. X-ray diffraction (XRD) results reveal the amorphous nature of the as-deposited film whereas the annealed films are found to be in the crystalline anatase phase. The surface morphology of the films at different annealing temperatures has been examined by atomic force microscopy (AFM). The in situ surface morphology of the as-deposited and annealed TiO2 films has also been examined by optical polaromicrograph (OPM). TiO2 films infatuated different structural and surface features with variation of annealing temperature. The optical studies on these films suggest their possible usage in sun-shielding applications.